module.exports = class Mcaptcha {
    constructor(options) {
      this.options = options;
      this.fontSize = options.height * 3 / 4;
      this.init();
      this.refresh(this.options.code);
    }
    init() {
      this.ctx = wx.createCanvasContext(this.options.el);
      this.ctx.setTextBaseline("middle");
      this.ctx.setFillStyle(this.randomColor(180, 240));
      this.ctx.fillRect(0, 0, this.options.width, this.options.height);
    }
    refresh(code) {
      let arr = (code + '').split('');
      if (arr.length === 0) {
        arr = ['e', 'r', 'r','o','r'];
      };
      let offsetLeft = this.options.width * 0.6 / (arr.length - 1);
      let marginLeft = this.options.width * 0.2;
      arr.forEach((item, index) => {
        this.ctx.setFillStyle(this.randomColor(0, 180));
        let size = this.randomNum(24, this.fontSize);
        this.ctx.setFontSize(size);
        let dis = offsetLeft * index + marginLeft - size * 0.3;
        let deg = this.randomNum(-30, 30);
        this.ctx.translate(dis, this.options.height*0.5);
        this.ctx.rotate(deg * Math.PI / 180);
        this.ctx.fillText(item, 0, 0);
        this.ctx.rotate(-deg * Math.PI / 180);
        this.ctx.translate(-dis, -this.options.height * 0.5);
      })
      this.ctx.draw();
    }
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    }
    randomColor(min, max) {
      let r = this.randomNum(min, max);
      let g = this.randomNum(min, max);
      let b = this.randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    }
  
  }